People told me that Assassin' Creed is marred by weird futuristic elements, but I disagree. These thoughts are spawned from the misconception that Assassin's Creed is a Crusade game, and this is a misconception that I myself shared when I started the game. By the time I was halfway through the game, all elements of "futurism" and the lack of interaction with historic Crusader figures and events were completely forgiven, because Assassin's Creed is actually more of a conspiracy theory game revolving around Holy Grail type artifacts and their influence in the game's modern and ancient time frames. Due to this, I actually enjoyed the futuristic elements.
As for the game play, it kept me both satisfied until the plot fully hooked me and at the same time greatly enhanced the themes of the game all of the way through. At its core Assassin's Creed is Prince of Persia: Sands of Time, with many of the same game play elements reappearing in Assassin's Creed. However, instead of having the elements of the environment set up like a puzzle with only a few solutions, it is just covered with all of the banisters and ledges and scaleable walls so that running and leaping through the cities is very fluid. Furthermore, the battles also require much more strategy than Prince of Persia and give the player more control.
In the end, I have decided that Ubisoft took their great game play they developed for Prince of Persia and turned it into something with a much deeper level of plot, character development, and freedom for the player; and what they came up with was Assassin's Creed.